CN115218708A

CN115218708A - Core for a transfer device and method of forming the same

Info

Publication number: CN115218708A
Application number: CN202210415738.9A
Authority: CN
Inventors: A·C·费尔顿; K·贝利; M·L·弗洛雷斯
Original assignee: Transportation IP Holdings LLC
Current assignee: Transportation IP Holdings LLC
Priority date: 2021-04-20
Filing date: 2022-04-20
Publication date: 2022-10-21
Also published as: EP4080037A1; US11725881B2; US20220333870A1

Abstract

The present application provides a core for a delivery device and a method of forming the same. The core includes a structure having a plurality of connected unit cells. At least one of the unit cells has one or more sidewalls that are curved and define a portion of an internal passage within and through the unit cell. The one or more sidewalls define a plurality of apertures and include a taper disposed between at least some of the apertures. Pits are defined along the outer surface of the cell lattice at the cones. The outer surface at least partially defines an external passage sealed to the internal passage by one or more sidewalls of the unit cell. The one or more sidewalls are configured to transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the internal passageway to the second fluid flowing in the external passageway without mixing the first fluid with the second fluid.

Description

Core for a transfer device and method of forming the same

Technical Field

The devices and methods described herein relate to devices that transfer heat between different fluids or filter particles.

Background

The cooling device transfers heat from one fluid across or through the barrier to the other fluid. One example of a cooling device is an Exhaust Gas Recirculation (EGR) cooler. As the exhaust gas and coolant flow through the cooler, the cooler transfers or absorbs heat from the recirculating engine exhaust to the coolant, such as water. The cooler has a housing in which a core is disposed. The core has separate channels for coolant and exhaust gases. The core is designed to enable heat transfer from one fluid to another and/or filtration of components from one fluid through the barrier without the need to mix the two fluids. One problem with these coolers is the complex core geometry that is manufactured and assembled within the housing of the cooler. The fluid channels of the core may meander through the core in a non-linear path to promote interaction of the fluid for heat transfer and/or filtration with the wall without unduly increasing fluid flow resistance and/or pressure drop through the core. Such complex geometries that provide tortuous flow passages while maintaining physical separation between the different fluids by the core can be constructed according to conventional processes such as casting.

Additive manufacturing can be used to print three-dimensionally or form complex core geometries. However, due to limitations of additive manufacturing techniques, printing complex repeating geometries often requires the formation of a support structure under some hypodermis (skin) surface to maintain design integrity and structural integrity. Support structures are undesirable for a variety of reasons, such as the support structures clogging the flow channels, being difficult or even detrimental to the core, and slowing down the additive manufacturing process. To avoid forming support structures within the core geometry, one approach is to reduce the size of the repeating units or crystal lattice in the core. However, reducing the cell size can undesirably increase flow resistance through the core, increase pressure drop through the core, decrease manufacturing speed, and increase manufacturing costs (e.g., more cells per given volume need to be printed as compared to when the cells are larger). This may reduce throughput and delivery effectiveness. It is desirable to have a system and method that is different from currently available systems and methods.

Disclosure of Invention

In one or more embodiments, a core is provided that includes a structure having a plurality of connected unit cells, and at least one of the plurality of connected unit cells has one or more sidewalls that are curved and have an inner surface that defines at least a portion of an internal passage within and through the unit cell. One or more sidewalls of the unit cell define a plurality of apertures such that a first fluid may enter the unit cell through one of the apertures and may exit the unit cell through another of the apertures. The one or more sidewalls include a taper disposed between at least some of the apertures of the unit cell. The one or more sidewalls have an outer surface and define a dimple on the cone along the outer surface. The one or more sidewalls have edges that extend around the apertures of the cell lattice. The edges of the different unit cells are connected to each other and the outer surfaces at least partially define an outer passage that is sealed from the inner passage by one or more sidewalls of the unit cells. The external passageway is configured to enable a second fluid to flow therethrough. One or more sidewalls of the unit cell are configured to transfer one or more portions of thermal energy from a first fluid or a component of the first fluid flowing in the internal passage to a second fluid flowing in the external passage without mixing the first fluid with the second fluid.

In one or more embodiments, a core is provided that includes a structure having a plurality of connected unit cells, and at least one of the plurality of connected unit cells has one or more sidewalls that are curved and have an inner surface that defines at least a portion of an internal passage within and through the unit cell. One or more sidewalls of the unit cell define at least four apertures such that a first fluid may enter the unit cell through one of the apertures and may exit the unit cell through another of the apertures. A portion of one or more sidewalls disposed between the three apertures is triangular in shape and the three apertures are spaced 120 degrees from each other along the circumference of the unit cell. The one or more sidewalls have edges that extend around the apertures of the cell lattice. Edges of different unit cells are connected to one another to at least partially define an external via sealed to the internal via of the unit cell and to internal vias of other unit cells by one or more sidewalls of the unit cell. The external passageway is configured to enable a second fluid to flow therethrough. One or more sidewalls of the unit cell are configured to transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the internal passage to the second fluid flowing in the external passage without mixing the first fluid with the second fluid.

In one or more embodiments, a method (e.g., for forming a core) is provided. The method includes additively manufacturing a core by sequentially depositing layers of material at least partially over each other along a build direction to form a structure consisting of a plurality of connected unit cells. At least one of the plurality of connected unit cells has one or more sidewalls that are curved and have an interior surface that defines at least a portion of an interior passage within and through the unit cell. One or more sidewalls of the unit cell define a plurality of apertures such that the first fluid may enter the unit cell through one of the apertures and may exit the unit cell through another of the apertures. The one or more sidewalls include a taper disposed between at least some of the apertures of the unit cell. The one or more sidewalls have an outer surface and define a pocket along the outer surface at the taper. The one or more sidewalls have edges that extend around the apertures of the unit cells, and the edges of different unit cells are connected to each other. The outer surface at least partially defines an external passage sealed to the internal passage by one or more sidewalls of the unit cell. The external passageway is configured to enable a second fluid to flow therethrough. One or more sidewalls of the unit cell are configured to transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the internal passage to the second fluid flowing in the external passage without mixing the first fluid with the second fluid.

Drawings

The subject matter of the present application may be understood by reading the following description of non-limiting embodiments with reference to the attached drawings, in which:

FIG. 1 illustrates one example of a transfer device;

FIG. 2 shows a first cross-sectional view of the device of FIG. 1;

FIG. 3 illustrates a cross-sectional view of a portion of a core of a delivery device according to an embodiment;

FIG. 4 shows an additional cross-sectional view of the device of FIG. 1;

FIG. 5 shows another cross-sectional view of the device of FIG. 1;

FIG. 6 shows another cross-sectional view of the device of FIG. 1;

FIG. 7 shows a first cross-sectional view of the transfer device along line 7-7 of FIG. 1;

FIG. 8 shows a second cross-sectional view of the transfer device taken along a plane orthogonal to line 7-7 in FIG. 1;

FIG. 9 illustrates another cross-sectional view of the transfer device along the line 7-7 shown in FIG. 1;

FIG. 10 is a perspective view of a core of a delivery device according to one embodiment;

FIG. 11 is a cross-sectional view of the core shown in FIG. 10;

FIG. 12 illustrates a first cross-sectional view of the core taken along line 12-12 of FIG. 11;

FIG. 13 illustrates a second cross-sectional view of the core taken along line 13-13 of FIG. 11;

FIG. 14 shows a third cross-sectional view of the core taken along line 14-14 of FIG. 11;

FIG. 15 shows a fourth cross-sectional view of the core taken along line 15-15 of FIG. 11;

FIG. 16 is a cross-sectional view of the core shown in FIG. 11, with an enlarged area showing the upper cone and the lower cone according to one embodiment; and

FIG. 17 shows a flow diagram of one example of a method for creating a delivery device or a component thereof.

Detailed Description

At least one embodiment described herein relates to a monolithic (e.g., monolithic) transfer device that accommodates thermal expansion of the core through unique flexible membrane connections at the inlet and outlet of the device. Such a flexible diaphragm may be more easily displaced than some known sliding joints and/or seals without creating unacceptable stresses in the housing (e.g., shell) or core. The transfer device may force a cooling medium (e.g., coolant) through the core without directly connecting the housing to the core. The cooling medium may be forced to increase the pressure of the coolant at some locations by forming different sized volumes at different locations (e.g., by additive manufacturing) between (a) the diaphragm and (b) the shell and the core, thereby forcing the coolant through a larger portion of the core (relative to some known coolers that use a sliding seal between the core and the shell). The flexible diaphragm may be integrally formed with the core and the shell by additive manufacturing to provide a fully integrated wall to minimize or even eliminate coolant leakage between the core and the shell. Printing the shell and core as a single piece allows for tight control of the interface between the two geometries (core and shell).

Alternatively, the core and shell described herein may be formed separately and then the core placed into the shell. For example, the housing may be cast, additively manufactured, injection molded, etc., and the core may be additively manufactured and placed in the housing. The flexible membrane may be formed as part of the shell or core or may be formed separately and then placed between the shell and core. The shell and core may then be welded together to form a fully integrated entity. Aspects and features of the design and fabrication methods may be determined using the features disclosed herein.

The flexible membrane and/or the core may enable the core to fit into a wide variety of application spaces using additive manufacturing. The housing may be made in a similar manner to avoid interference with existing components to facilitate retrofitting.

With respect to some known EGR coolers, the devices described herein may accommodate thermal cycling without a sliding interface to maximize or extend the useful life of the device. Furthermore, because there is no moving or sliding interface, there is no need to seal with gaskets, O-rings, etc., so the device can withstand extreme temperature conditions. One such condition is a dry run condition of the engine, in which engine exhaust gas flows through the device, but no cooling medium flows through the device. This condition can expose the device to temperatures in excess of 1,000 degrees fahrenheit (or 540 degrees celsius). In turn, extreme temperatures may lead to extreme thermal expansion. The flexible membranes of the embodiments described herein can flex and accommodate thermal expansion.

Other embodiments described herein relate to a core or core of a delivery device. The core may be defined or designed with repeating interconnected unit cells that define internal passages for one fluid through the unit cell and external passages for another fluid outside the unit cell without physically mixing the two fluids with one another. For example, the internal passageway is not in fluid communication with the external passageway. The unit cell has sidewalls between the inner and outer passages, allowing thermal energy (e.g., heat) to transfer from the hotter fluid to the cooler fluid through the sidewalls. Optionally, the sidewalls may be defined or designed to allow one or more components to pass (e.g., filter) from the first fluid through the sidewalls into the second fluid. The first fluid and/or the second fluid may optionally comprise more than one fluid type, composition or compound. For example, the first fluid may be a coolant introduced into the core interior passage, while the second fluid may be a plurality of different fluids introduced into the exterior passage. A plurality of different fluids may mix with each other within the core and transfer heat to the coolant through the thin sidewalls.

According to an embodiment, the wick has a complex repeating geometry that separates the fluids and is printable without forming a support structure. The geometry of the core allows the selection of a relatively large, unsupported cell size. Larger unit cells may provide less flow resistance and pressure drop (e.g., higher fluid throughput) through the core relative to smaller unit cells. The unit cells are hollow, so increasing the size of the unit cell relative to a smaller unit cell can actually reduce the amount of material deposited during the additive manufacturing process, thereby increasing printing speed and reducing printing and/or material costs.

The ability to additively manufacture the core without a support structure also enables the core to be formed into a custom shape based on the particular application. In an EGR cooler, the core may be printed to conform to a particular internal volume or form factor of the housing. Alternatively, the core may be integrally formed with the housing during a common additive manufacturing process to provide a monolithic (one-piece) EGR cooler. Integrally forming the core with the outer shell eliminates seams between components, which may advantageously eliminate potential leak paths during use and operation of the EGR cooler.

Fig. 1 shows one example of a delivery device 100. The device may be used to transfer energy or components between two media. For example, the device may transfer thermal energy (e.g., heat) from one fluid to another (to cool one fluid) or may transfer components from one fluid to another (to filter components from one fluid). The device includes a housing 102 in which an internal heat transfer core and a flexible membrane (both shown in FIG. 2) are disposed. The housing has a first inlet 110 for receiving a first fluid 112 and a second inlet 114 for receiving a second fluid 116. The first and second fluids may be gases and/or liquids. For example, the first fluid may be a coolant or cooling medium, such as a heat transfer fluid (e.g., water, refrigerant, other synthetic or natural fluid). The second fluid may be exhaust gas from the engine or may be another liquid. The second fluid may be at a higher temperature than the first fluid prior to entering the device.

The housing further comprises a first outlet 120 through which the first fluid is directed out of the housing, and a second outlet 118 through which the second fluid is directed out of the housing 118. As described herein, the core has an inner passage (as shown in fig. 2) through which a first fluid flows through the core from a first inlet to a first outlet, and an outer passage (as shown in fig. 2) through which a second fluid flows through the core from a second inlet to a second outlet. As the first and second fluids flow through the respective inner and outer passages, heat may be transferred from the second fluid to the first fluid (through or via the material forming the core). Alternatively, the material forming at least a portion of the core may filter one or more components from the second fluid to the first fluid (or from the first fluid to the second fluid). Alternatively, the first fluid may comprise a plurality of different fluids mixed together within the internal passage of the core. Alternatively, the second fluid may comprise a plurality of different fluids mixed together within the outer passage of the core.

The inner passage may maintain the first fluid separate from the second fluid, and the outer passage may maintain the second fluid separate from the first fluid. The internal passageway may direct the first fluid from the first inlet to the first outlet. The first outlet may direct the first fluid (which has now been heated by the second fluid or has received one or more components from the second fluid) to an apparatus or system that cools (or filters) the first fluid and returns the first fluid to the first inlet. The external passageway may direct the second fluid from the second inlet to the second outlet. The second outlet may direct the second fluid (which has now been cooled by the first fluid or which has caused one or more components to be removed and transferred to the first fluid) back to the engine (in an EGR engine) or to another location.

Fig. 2 shows a first cross-sectional view of the device of fig. 1. The cross-section shown in fig. 2 is along a plane parallel to the plane of fig. 1 and extending through the axial center of the core. The internal heat transfer core 204 within the housing comprises a unitary structure or web of material 201 shaped such that it forms a first internal passage 522 and a second internal passage 524. The first and second

inner passages

522, 524 of the core are also referred to herein as inner and outer passages, respectively. Alternatively, the core may be formed from a plurality of bodies or webs of material shaped to form the internal and external passageways.

The device includes a flexible membrane 206, the flexible membrane 206 being coupled to the core and extending from the core to an inner surface 208 of the shell. The diaphragm is flexible in that it can bend or otherwise change shape when subjected to more force or displacement (subject to the same force or displacement) than the shell and/or core. The diaphragm forms a flexible transition between (a) each of the first and second inlets of the housing and (b) the core. The flexible membrane forms a seal to prevent the first fluid flowing through the internal passage of the core from flowing into the external passage of the core. The flexible diaphragm can accommodate different variations in the size of the shell and core due to thermal variations. For example, the shell and core may expand different amounts or distances due to different sizes of the shell and core (even when the shell and core are formed as a monolithic body and from the same material). Due to the differential expansion of the shell and the core, the flexible diaphragm may flex without tearing or otherwise breaking the seal between the shell and the core. This keeps the inner and outer passages of the core separate.

Fig. 3 shows a cross-sectional view of a portion of a core according to an embodiment. The cross-section shown in fig. 3 is along a plane parallel to and offset from the plane of fig. 2. The inner passageway 522 is located on one side of the body or web of material of the core, while the outer passageway 524 is located on the opposite side of the body or web of material of the core. For example, the body or web of material includes thin sidewalls 210 separating the internal passages from the external passages.

The sidewalls are part of the unit cells 212 of the core, and these unit cells 212 are a geometric shape that repeats throughout the core. The unit cells are connected to each other. For example, the core is a structure having a plurality of connected unit cells. In one or more embodiments, the cell lattice shape is substantially spherical, as defined by sidewalls, such as the circular cross-section shown in fig. 3. The shape of the peripheral unit cell positioned along the cylindrical side of the core may be distorted from spherical as necessary to provide the desired overall size and/or shape of the core. In other embodiments, the unit cell may be other shapes. Other suitable shapes may include cubes, parallelepipeds, prisms, and the like. An internal passageway is defined within and extending through the cell lattice. The external vias are located outside the cell lattices and represent unoccupied spaces between the cell lattices.

As shown in fig. 3, the internal passageway is separated from the external passageway by a sidewall. In fig. 3, the inner vias within the two unit cells are filled with diagonal lines to clearly show the difference between the inner vias and the outer vias surrounding the inner vias in the illustrated cross-sectional view. The side walls may be relatively thin. A suitable sidewall thickness may be less than 3 millimeters (mm). The sidewalls of the unit cells are interconnected at edges 806 (as shown in fig. 10) to fluidly connect the internal passages of the entire core and to maintain the first and second fluids physically separated from one another. In one embodiment, heat may be transferred between the first fluid and the second fluid through the sidewall without mixing any other portion of the first fluid and the second fluid together in the inner passage or the outer passage. Alternatively, the sidewall may include apertures that filter one or more components from the second fluid to the first fluid (or from the first fluid to the second fluid) without any other portion of the first fluid and the second fluid mixing together in the inner or outer passages. In the illustrated embodiment, the fluid within the inner passage is a gas and the fluid within the outer passage is a coolant. Alternatively, the gas in the inner passage may be hot gas exhausted from the engine and the coolant in the outer passage may be water. As water flows along the external pathways through the tortuous paths between the cell lattices, the water may absorb heat from the gas through the sidewalls of the cell lattices. Water enters the core through the inlet opening 214 of the outer passage along the outer peripheral surface of the core.

Fig. 4, 5 and 6 include additional cross-sectional views of the device shown in fig. 1. The cross-sectional views of fig. 4, 5 and 6 are taken along the same plane as the cross-sectional view of fig. 2. The flexible diaphragm has a curved conical shape extending inwardly from the inner surface of the outer shell to the core. This taper provides a tapered transition between the shell and the core. The tapered transition may be controlled to vary the length (e.g., distance from the inner surface of the shell to the core) and/or the angle of intersection with the shell and the core such that the flexible membrane may be included within various shapes of the core and/or the shell. With the ability to customize the size and/or shape of the flexible membrane, the delivery device can be efficiently determined or designed and packaged for space-constrained applications. While the shell is shown as cylindrical, the core and/or shell may be of another shape, with a flexible membrane extending between the core and shell and sealing the shell to the core. For example, the shell may be rectangular, with the flexible membrane extending between and sealing the shell to the core.

In the illustrated embodiment, the flexible membrane is flat. For example, the septum may have a smooth conical shape without undulations, waves, dimples, protrusions, and the like. Alternatively, the diaphragm may have an uneven surface with undulations, waves, dimples, protrusions, etc.

As shown, the flexible diaphragm may be thinner than the housing. The inner surface 432 of the flexible membrane faces the core and faces away from the portion of the inner surface of the housing between the second inlet and the second outlet of the housing. The inner surface of the flexible diaphragm may be oriented at an angle of less than forty-five degrees to the inner surface of the housing. Alternatively, the inner surface may be oriented at an angle of less than thirty degrees or less than fifteen degrees from the inner surface of the housing. An opposite outer surface 430 of the flexible diaphragm faces away from the core and may face a portion of the inner surface of the outer shell between the second inlet and the second outlet. The outer surface of the flexible diaphragm may be oriented at an angle of greater than forty-five degrees to the inner surface of the housing. Alternatively, the outer surface may be oriented at an angle of greater than fifty-five degrees or greater than seventy-five degrees from the inner surface of the housing.

Fig. 7 shows a first cross-sectional view of the transfer device along line 7-7 in fig. 1. Fig. 8 shows a second cross-sectional view of the transfer device. The cross-sectional view in fig. 8 is taken along a plane orthogonal to line 7-7 in fig. 1. As shown in fig. 1, the housing includes elongated recesses 122 on opposite sides of the housing. The recess may be elongate in a direction extending from the second inlet to the second outlet. As shown in fig. 8, the recess may be provided midway along the circumference of the housing between the first inlet and the first outlet. For example, the notches may be on opposite sides of the housing. Alternatively, the recess may be located in another position and/or the housing may comprise more than two recesses. The recess may reduce the distance or spatial gap between the inner surface of the shell and the core. For example, the core may be positioned farther from the recess, a greater distance 434 from the inner surface of the shell (as shown in fig. 5 and 8), and a closer distance 600 from the recess (as shown in fig. 7 and 8).

The smaller distance between the shell and the core at the recess helps to force the first fluid to flow from the first inlet to the first outlet and away from the outlet. The notches reduce the flow of the first fluid through the first inlet to squeeze the first fluid and help force the first fluid toward the first outlet.

Figure 9 shows another cross-sectional view of the transfer device along the line 7-7 shown in figure 1. In this illustrated embodiment, the flexible diaphragm engages an inner surface of the housing having a circular interface. For example, the flexible diaphragm and/or the housing may form rounded corners at one or both of the interface between the inner surface of the flexible diaphragm and the inner surface of the housing and the interface between the outer surface of the flexible diaphragm and the inner surface of the housing, rather than forming corners or interfaces between straight lines. The flexible diaphragm and/or the housing may have

fillets

726 and 728 on opposite sides of an interface between the flexible diaphragm and the housing. These rounded corners may be rounded interfaces that increase the flexibility of the diaphragm (as compared to interfaces that do not include rounded edges or rounded corners). The radius of curvature of the fillet may be smaller than the bullnose as shown in FIG. 9.

Fig. 10 is a perspective view of a core of a delivery device according to one embodiment. The unit cells of the core each have one or more curved sidewalls. The inner surface 800 of the one or more sidewalls defines at least a portion of an internal passageway that extends within and through the respective unit cell. The outer surface 802 of the one or more sidewalls defines at least a portion of the external passage in the intervening space between the unit cells. The core has a height extending from a bottom end 810 to (opposite the bottom end) a top end 812. In the illustrated embodiment, the core is generally cylindrical to conform to the interior of the shell. For example, the core has an outer side 814 that is circumferential and extends from the top end to the bottom end. The surface along the outside has grooves and undulations due to the curved sidewalls of the unit cell. The internal passages through the unit cell cause the first fluid to flow generally along the vertical height of the core, e.g., from the top end down and out through the bottom end. The outer passages enable the second fluid to flow laterally, radially and circumferentially (as well as vertically). For example, the second fluid may enter the outer passage through the cylindrical outer side of the core, as shown in fig. 3 and 8.

The unit lattices in the core are arranged in an array. In an embodiment, the crystal lattice is arranged in a plurality of rows 816 stacked along the height of the core. The illustrated embodiment shows at least a portion of four

rows

816a, 816b, 816c, 816d of unit cells. Each row includes a plurality of unit cells spaced apart from each other. The cell lattices in a row may be staggered or offset from the cell lattices in a row above or below. For example, a single unit cell may be at least partially disposed over multiple unit cells in the row. Due to the staggering of the positions of the unit cells, the first fluid is forced to wriggle through internal passages rather than a substantially free-fall movement through the core, thereby promoting fluid-side wall contact interaction. The fluid-sidewall interaction thereby produces heat transfer and/or material transfer. In an embodiment, a given unit cell in an intermediate row (e.g., 816b, 816 c) is interconnected with unit cells in upper and lower rows. Alternatively, the unit cell may not be directly fluidically connected to other unit cells in the same row.

The size and shape of the unit cells of the core may be identical to each other, except that the peripheral cells along the outer side are distorted to maintain the designated size and shape of the core. The sidewalls of the unit cells along the outside of the core may be flatter (e.g., less curvature) relative to the curvature of the sidewalls along the interior unit cells. The outer sidewall closes the internal passage to maintain mechanical separation between the first fluid and the second fluid.

For example, the array of unit cells of the core shown in fig. 10 is smaller than the unit cells of the core shown in fig. 8, thereby demonstrating that the number and size of the unit cells can be selected based on application specific parameters. Suitable parameters that may be considered may include the amount of thermal energy transfer, fluid flow resistance, fluid pressure drop, and the like. A core in accordance with at least one embodiment is formed with a relatively large cell size to reduce flow resistance and pressure drop and improve manufacturing efficiency (e.g., less material and printing) while providing sufficient fluid-sidewall interaction to achieve desired transfer performance.

The sidewalls of the cell lattice define a plurality of apertures 804, the apertures 804 representing portions of internal passages through the cell lattice. For example, the first fluid may enter the respective unit cell through one orifice of the cell and may exit the unit cell through another orifice. In one embodiment, the orifices of a unit cell are connected to other unit cells to fluidly connect internal passages through the core. Each aperture of a unit cell may be fluidically connected to a different unit cell. For example, the three apertures of the first unit cell may be connected to the second unit cell, the third unit cell, and the fourth unit cell, respectively. The sidewalls may have edges 806 that extend around the lattice apertures. The edges of the different unit cells are connected to each other to interconnect the internal vias and seal the internal vias from the external vias.

In an embodiment, edges connecting the unit cells are integrally connected to each other to define a seamless interface between the unit cells. For example, the core may be a single monolithic structure in which the unit cells are interconnected at a seamless interface. The material composition of the core may be selected based on the application specific coefficients. For example, a material having good thermal conductivity, such as one or more metallic materials, may be used for heat exchange applications of the transfer device. Other types of materials, such as polymeric materials, ceramic materials, or composite materials, may be used to form a core for filtration applications in which at least one component of the first fluid or the second fluid passes to and/or through the sidewalls of the cell lattice.

According to at least one embodiment, the core is produced by additive manufacturing. The core is formed by depositing layers of build material sequentially over each other in the build direction at least partially to ultimately form the structure shown in fig. 10. The build material may be a powder that is deposited in a bed and then selectively heated to provide the specified location, size and shape of each layer according to the design file. Alternatively, the build material may be a filament that is heated by a movable actuator head and selectively deposited to provide a specified location, size, and shape for each layer according to a design file. In the illustrated embodiment, the core may be additively manufactured in an upward build direction 808. For example, the bottom end 810 may be initially formed, and subsequent layers stacked on top of each other until the top end 812 is finally formed, thereby completing the build process. The manufacturing steps can be iteratively improved using the features disclosed herein.

Fig. 11 is a cross-sectional view of the core shown in fig. 10. The cross-sectional view in fig. 11 is taken along a plane orthogonal to the core tip plane in fig. 10, and this cross-sectional plane may bisect the core. Fig. 11 shows an isometric view of two complete unit cells (represented by dashed circles) and a plurality of partial unit cells. Fig. 11 shows four apertures 804 defined by the sidewalls of each complete cell lattice. For example, two orifices are taken laterally at the upper right and lower left regions of the lattice, and two orifices are shown at the upper left and lower right regions that extend a depth into the core. In one embodiment, the cell lattice has a total of six orifices, the other two being omitted from fig. 11 for cross-sectional illustration. Six orifices provide flow channels to connect each unit cell with six other unit cells. In alternative embodiments, the cell lattice may have a different number of apertures.

As shown in fig. 10 and 11, the complete unit cell is spherical. For example, the portions of the sidewalls of each unit cell between the apertures have a convex curvature relative to the center of the unit cell to define spheres. Alternatively, the unit cell may be at least slightly elongated to define an ellipse or oval.

The unit cells in adjacent rows may be staggered. The internal passages may extend at an oblique angle relative to the row plane and the vertical height of the core, which promotes fluid and sidewall interaction. A line 821 extending from a center point 822 of the first cell to a center point 822 of a second cell connected to the first cell defines an angle 824 of not less than 30 degrees and not more than 60 degrees with respect to a row plane (e.g., a horizontal plane). According to a more preferred range, the angle may be between 35 degrees and 45 degrees. More specifically, the angle may be between 40 and 42 degrees. These angles may be selected to ensure that the additively manufactured core has sufficient printability and print quality, and may also provide efficient cell row encapsulation.

The dimensions of the inner and outer passages vary with their length. Along the internal passageway, the orifice defines a narrowest or restricted dimension 818. The cell lattice apertures may be larger than the narrowest dimension or restriction dimension 820 in the outer passage. The inner passage may occupy more space within the core than the outer passage. The flow size and the size of the passages may vary depending on the type of fluid flowing through the passages and/or the desired transfer occurring between the fluids through the sidewalls. In one embodiment, the first fluid flowing through the inner passage is a hot gas and the second fluid flowing through the outer passage is a coolant designed to absorb heat from the gas. In alternative embodiments, the size of the unit cells and/or the spacing between the unit cells may be varied such that the restriction in the outer passages is greater than the restriction in the inner passages, and/or such that the outer passages occupy more space in the core than the inner passages.

The cell lattice includes tapered features or pyramids 826 disposed between at least some of the apertures of the respective cell lattice. The taper 826 protrudes toward the center point of the cell lattice. The pyramid has a vertex 830, the vertex 830 being located between the center point of the lattice and the sidewall portion at the base of the pyramid. The taper 826 can be hollow and the portion of the taper along the outer surface of the sidewall can define a pocket 828. Some of the dimples of the cone are shown in the perspective view of fig. 10.

The taper is located at the bottom of the curved unit cell. For example, the cones may be disposed at the lowermost portion of the unit cell with respect to the direction of gravity. In one embodiment, the cones are located along the center lines of the unit cells. The tapering of the base or bottom of the unit cell enhances the printability of the core without the need for a support structure when the unit cell is spherical or otherwise curved. For example, as shown in fig. 11, the base of the lattice is unsupported. Forming the inflection points along the side walls at the base avoids the problems associated with printing relatively flat surfaces and/or curved nadirs without any support. The taper enables the unit cell to remain substantially spherical without the need for a printed structure to support the islands of build material during fabrication. The taper may also prevent fluid from accumulating within the sidewalls of the cell lattice. For example, if the first fluid is a liquid, it will flow from the cone to the orifices surrounding the cone.

In one embodiment, the sidewalls of the unit cell also include a second tapered feature or taper 832 along the top of the unit cell. The second taper is spaced from the first taper and disposed relative to the first taper between different sets of apertures of the unit cell. The first cone is referred to herein as lower cone 830 and the second cone is referred to herein as upper cone 832. The upper cone is hollow and defines a pocket 834. The upper cone protrudes relative to the core in the same direction as the lower cone. For example, both cones project towards the tip of the core. The recess of the upper cone is defined along the inner surface of the sidewall. Optionally, the upper cone may be collinear with the lower cone. An upper cone may be included to improve the printability of the cell lattice in the core, similar to the inclusion of a lower cone. The presence of the upper pyramid can eliminate a relatively flat area on top of the curved unit cell that, if not supported by an underlying layer, can be difficult to print reliably.

FIG. 12 illustrates a first cross-sectional view of the core taken along line 12-12 of FIG. 11. Figure 13 illustrates a second cross-sectional view of the core taken along line 13-13 shown in figure 11. Figure 14 shows a third cross-sectional view of the core taken along line 14-14 of figure 11. Figure 15 illustrates a fourth cross-sectional view of the core taken along line 15-15 shown in figure 11. The illustrations in fig. 12-15 show top views of the core shown in fig. 10 taken along different parallel planes. The cross-sections shown in fig. 12-15 may indicate different time stages of the build process when the core is additively manufactured from bottom to top. The core is formed using relatively thin sidewalls to improve printing efficiency by limiting the amount of material to be printed and to provide relatively large pathways inside and outside the crystal lattice to limit fluid flow resistance and pressure drop.

The core cross-section shown in fig. 12 includes a circle 900 at the radial center and six semi-circles 902 around the center circle. These shapes represent portions of the seven unit cells in the first row of the core. Three small circular openings 904 are arranged in a triangle around the center circle. The small openings represent the portions of the pits of the lower pyramid of the upper row of unit cells. The circular segment 906 of the sidewall defining the small opening is part of the lower cone shown in fig. 11.

The cross-section of the core shown in fig. 13 includes three complete unit cells and three partial peripheral unit cells that are located in a second row above the cells in the first row shown in fig. 12. The cell lattice in the second row is intercepted by the cut lines 13-13. Three complete unit cells are spaced apart in a triangular arrangement. An external via is defined in a space between the second row of unit cells. In one embodiment, each complete unit cell is built on top of and individually connected (by the edges of the apertures) to the plurality of unit cells in the lower row. Each complete unit cell may be disposed over portions of three underlying unit cells.

Within the circular profile of each unit cell is a portion 910 of the sidewall disposed between the plurality of apertures. The portion defines the base or bottom of the unit cell and includes a lower taper. In fig. 13, the visible side wall portion is generally triangular and is located between the three apertures. The three orifices are spaced 120 degrees apart from each other along the circumference of the unit cell. The lower cone may be centered and located equidistant between the three apertures disposed around the triangular portion. Each of the three orifices visible in each complete unit cell is fluidly connected to a different unit cell in the row below. For example, the apertures connect each cell lattice to three underlying cell lattices, with the respective cell lattice extending at least partially over and overlapping the underlying cell lattice. When the first fluid flows through the internal passages of a corresponding unit cell, the first fluid is divided into three sub-streams into three connected cells. Fig. 13 also shows the top of the upper cone of the centrally located unit cell.

The core cross-section shown in fig. 14 includes three complete unit cells and three partial peripheral unit cells in a third row disposed on top of the second row of cells. The arrangement of the unit cell in the third row is opposite to (e.g., inverted with respect to) the arrangement of the unit cell in the second row. For example, the three full cell lattices in fig. 14 are arranged in a triangular pattern similar to that of fig. 13, but the triangular pattern is flipped 180 degrees relative to the triangular arrangement in fig. 13. In one embodiment, the sidewalls of the complete unit cell have three apertures fluidly connecting the respective unit cell to three different unit cells in a row above. For example, the lattice 212a in the second row is fluidically connected to three

lattices

212b, 212c, 212d in the third row. The complete unit cell according to the illustrated embodiment includes a total of six apertures including three apertures connected to the cells in the lower row and three apertures connected to the cells in the upper row. The first fluid may enter the cell through one or more orifices and may exit the cell through one or more other orifices.

Fig. 15 is a plan view of the core showing the tip. The top of the core includes a plurality of incomplete unit cells located in a fourth row of the core above the unit cells in a third row shown in cross-section in fig. 14. The arrangement and shape of the unit cell shown in fig. 15 are similar to those of the unit cell in the first row shown in fig. 12. In one embodiment, each row of unit cells in the core has one of three lattice arrangements, and the rows alternate along the height of the core in a repeating pattern through the three lattice arrangements. In alternative embodiments, the unit cells may be arranged in a different number of repeating configurations.

FIG. 16 is a cross-sectional view of the core shown in FIG. 11, with an enlarged region showing the upper taper 832 and the lower taper 826, in accordance with an embodiment. In the illustrated embodiment, the lower cone is larger than the upper cone. For example, the base of the lower cone is wider than the base of the upper cone. The lower cone is also taller from base to apex than the upper cone. The lower cone of dimples 828 has a larger volume than the upper cone of dimples 834. The lower cone may be larger than the upper cone for printability reasons. In alternative embodiments, the upper cone and the lower cone may have the same dimensions, or the upper cone may be larger than the lower cone.

The core may be manufactured to have a thin wall as a whole. For example, the wall thickness may be less than 3mm even at the thickest part of the side wall. In one embodiment, the sidewall thickness is between 0.3mm and 1.5mm (inclusive). The orifice diameter may be significantly larger than the wall thickness. For example, the orifice diameter may be at least 3mm. In one embodiment, the orifice may be at least ten times the wall thickness. The orifice diameter in such embodiments may be up to 15mm or more. Alternatively, the thickness of the sidewalls may vary within this relatively narrow range. For example, the sidewall along the lower cone may be thicker than the sidewall segments extending from the lower cone. Alternatively, the sidewall along the upper cone may also be thicker than the sidewall segments extending from the upper cone. The lower cone wall thickness may be greater than the upper cone wall thickness to support a greater size and greater curvature of the lower cone relative to the upper cone.

The thin walls enable the core to have relatively large cell lattices and apertures. For example, for a complete lattice that does not deform along the periphery of the core, the unit cell size may be between 10mm and 30 mm. For a spherical unit cell, the unit cell size refers to the inner diameter of the sidewall. In one embodiment, the cell size is about 20mm. The lattice size may be selected based on application specific factors (such as fluid throughput and transfer characteristics) rather than printability factors. For example, known cores having a repeating geometry either have a lattice size that is significantly smaller to avoid the use of internal support structures within the core, or have a lattice size that is larger but includes internal support structures. Known cores do not include large lattice sizes without internal support structures.

FIG. 17 shows a flow diagram of one example of a method 1000 for creating a delivery device or a component thereof. The method may be used to create one or more embodiments of the delivery device shown and/or described herein. The method may be performed by an additive manufacturing system (e.g., a three-dimensional printing system) that uses an input file to automatically print a delivery device. Suitable input file formats may include STL, OBJ, AMF, 3MF, etc. At step 1002, a layer of material is deposited onto a work surface. For example, the first layer of material used to form the transfer device may be printed from one or more filaments onto the work surface.

At step 1004, an additional layer of material is deposited onto the underlying material. The additional layer may be at least partially printed onto a layer of material deposited prior to the additional layer. At step 1006, it is determined whether the fabrication of the transfer device is complete. If additional layers are to be deposited to complete the formation of the entire transfer device, the flow of the method may return to step 1004 so that one or more additional layers may be deposited as described above (until the creation of the transfer device is complete). The layers may be deposited at least partially sequentially on top of each other to form the shape of the shell, the flexible membrane and the core. By "at least partially" is meant that the entire layer or a portion of the entire layer can be printed over the underlying layer. If the creation of the delivery device is complete, the flow of the method may continue to step 1008. At step 1008, the transfer device is removed from the work surface. The transfer device may then be used to transfer energy and/or components between the fluids, as described above.

Alternatively, the method may be used to form a component of a transfer device without forming at least one other component of the transfer device. For example, the core may be additively manufactured by depositing layers of material at least partially sequentially over each other in the build direction. Additive manufacturing may be performed by a three-dimensional printing system according to instructions entered into a design file to produce a core according to embodiments described herein. For example, the method may be performed to print the cores shown in fig. 10-16.

Suitable processes include, for example, laser powder bed fusion, electron beam powder bed fusion, directed Energy Deposition (DED), and binder jetting (binder jetting). Laser powder bed fusion involves depositing a layer of powder on a build plate (build plate) and fusing selected portions of the powder using an ytterbium fiber laser scanning the CAD pattern. Laser powder bed fusion may include selective laser melting or sintering. Printing of at least a portion of the core and/or transfer device may be performed using printing of a very fast DED. For example, the DED may be used to print the outer shell of a delivery device and then may be fused directly to a flexible membrane connected to a core. Adhesive jetting manufactures parts by inserting metal powder and polymer binding agent(s) that are used to bond particles and layers together without the use of laser heat. The material of the core may be selected based at least in part on the proposed additive manufacturing method. For example, a binder-blasting material comprising a binder and a metal (or ceramic or cermet) may produce a green body (e.g., a pre-sintered shape). The green body may be in a final shape or may be shaped so that a sintered form (sintered form) is in the final shape.

The core of a delivery device according to embodiments described herein is a three-dimensional structure having a lattice of interconnected cells arranged in a regular repeating pattern. The properties and characteristics of the core may be selected based on application specific parameters and desired functionality. For example, properties such as the shape of individual (and repeating) lattices within the structure may be selected to increase structural strength, thermal conductivity, flow or throughput through the core, surface area for fluid-film interaction, and the like. Alternatively, the angle or slope of the sidewalls, the thickness of the sidewalls, the material composition of the sidewalls, the dimensions of the sidewalls, and other characteristics of the sidewalls, such as density, relative density, porosity, etc., may be selected to achieve a desired strength, thermal conductivity, surface area, density, heat dissipation capability, etc. Relative density refers to the density of the material divided by the density of the core. Porosity represents a measure of the amount of void material (e.g., air) that occupies a volume.

The properties of the entire core may be uniform or may vary with the height, radial thickness, etc. of the core such that one or more properties in one region of the core may differ from another region of the core. The shape, size, thickness, or spacing of the unit cells may be varied throughout the core structure to improve the performance characteristics of the heat exchanger. For example, cell lattice size (e.g., diameter), orifice diameter, spacing between cell lattices, ratio between dimensions of the inner and outer passages, and/or sidewall thickness may be selectively varied to control fluid flow, heat transfer, material transfer (e.g., filtration) into and/or through the sidewall, and/or the like. Varying the flow resistance may help spread the fluid to an area that naturally receives less fluid flow than other areas. The unit cells closer to the radial center of the core may be smaller or closer together than the unit cells closer to the periphery or outer side of the core. The small size may increase the flow resistance through the inner and/or outer passages located closer to the center, which may force more fluid to the periphery.

The core may be formed of at least one plastic, ceramic and/or metallic material. The plastic material may comprise or represent epoxy, vinyl ester, polyester thermosetting polymers such as polyethylene terephthalate (PET), polypropylene, etc. The ceramic material may comprise or represent silicon dioxide, aluminum oxide, silicon nitride, or the like. The metallic material may include or represent an aluminum alloy, a titanium alloy, a cobalt-chromium alloy, stainless steel, a nickel alloy, or the like. The core may be a composite material comprising a mixture of materials such as plastic and ceramic, ceramic and metal (referred to as a cermet composite), and/or plastic and metal. Alternatively, the core may represent a reinforced composite material, such as a fibre reinforced plastic. The fiber reinforced plastic may include fibers embedded within a plastic matrix layer. The fibers may be carbon fibers, glass fibers, aramid fibers (e.g.,

) Basalt fibers, naturally occurring bio-fibers such as bamboo, and/or the like. The reinforced composite may be reinforced with other shaped materials besides fibers, such as powders or bars in other embodiments. The reinforcement may be embedded in any of the plastics listed above. The cermet composite material may be comprised of any of the ceramics and metals listed above. For an additive printing process, the material may be provided in particulate form, for example in powder form, and the printing system selectively fuses the particles together to form each layer of the solid build member.

The additive manufacturing system and/or post-printing instruments may be controlled to determine and provide the core with a particular surface finish that affects how the core interacts with the fluid flowing through the core. For example, a rougher surface finish may increase flow resistance, increase heat transfer, and/or increase material transfer through the sidewall relative to a smoother surface finish. Optionally, the surface finish may be varied from core to selectively control fluid flow and/or transmission conditions throughout the core. Each aspect may be determined using the methods disclosed herein.

In one or more embodiments, a core (e.g., for a delivery device) includes a structure having a plurality of connected unit cells, and at least one unit cell of the plurality of connected unit cells has one or more sidewalls that are curved and have an inner surface that defines at least a portion of an internal passage within and through the unit cell. One or more sidewalls of the cell lattice define a plurality of apertures such that the first fluid may enter the cell lattice through one of the apertures and may exit the cell lattice through another of the apertures. The one or more sidewalls include a taper disposed between at least some of the apertures of the unit cell. One or more of the sidewalls has an outer surface and a pocket is defined along the outer surface at the taper. One or more of the sidewalls has an edge that extends around the aperture of the cell lattice. The edges of the different unit cells are connected to one another and the outer surfaces at least partially define an external passage sealed from the internal passage by one or more sidewalls of the unit cells. The external passageway is configured to enable a second fluid to flow therethrough. One or more sidewalls of the unit cell are configured to transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the internal passage to the second fluid flowing in the external passage without mixing the first fluid with the second fluid.

Optionally, the taper protrudes toward a center point of the unit cell. Optionally, the unit cell defines at least three apertures and the cones are located equidistant from the at least three apertures. The cones may be located equidistant from three orifices spaced 120 degrees apart from each other along the circumference of the unit cell. Optionally, the unit cell has a spherical shape defined by a portion of one or more sidewalls of the unit cell between the apertures and spaced from the taper. The wall thickness of the sidewalls of the unit cell may be not less than 0.3mm and not more than 1.5mm. The cell lattice may have an orifice diameter at least ten times the wall thickness of one or more sidewalls of the cell lattice. Optionally, the cell lattice has an aperture diameter larger than the diameter of the external passage. Optionally, the core is a single monolithic body, the plurality of unit cells being joined together at a seamless interface. The structure may be composed of a metallic material, a polymeric material, or both a metallic material and a polymeric material. Alternatively, the unit cells are arranged in rows at least partially stacked above each other, and a line extending from a center point of one unit cell in the first row to a center point of another unit cell in the second row defines an angle of not less than 30 degrees and not more than 60 degrees with respect to a plane of the first row.

Optionally, the taper is a first taper and the one or more sidewalls of the unit cell comprise a second taper disposed between a set of apertures of the unit cell different from the apertures between which the first taper is disposed. The first cone and the second cone protrude in a common direction. The structure has a height extending from a bottom end of the structure to a top end of the structure, and the first taper of the unit cell is disposed elevationally below the second taper of the unit cell. The first taper size may be greater than the second taper size.

In one or more embodiments, a core (e.g., a core for a delivery device) includes a structure having a plurality of connected unit cells, and at least one unit cell of the plurality of connected unit cells has one or more sidewalls that are curved and have an inner surface that defines at least a portion of an internal passage within and through the unit cell. One or more sidewalls of the cell lattice define at least four apertures such that the first fluid may enter the cell lattice through one of the apertures and may exit the cell lattice through another of the apertures. Portions of one or more sidewalls disposed between three of the apertures are triangular in shape and the three apertures are spaced 120 degrees apart from each other along the circumference of the unit cell. The one or more sidewalls have edges that extend around the apertures of the unit cell. The edges of the different unit cells are connected to one another to at least partially define external passages that are sealed by one or more sidewalls of the unit cells to isolate the internal passages of the unit cells from the internal passages of other unit cells. The external passageway is configured to enable a second fluid to flow therethrough. One or more sidewalls of the unit cell are configured to transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the internal passage to the second fluid flowing in the external passage without mixing the first fluid with the second fluid.

Optionally, the portion of the one or more side walls having a triangular shape comprises a cone. One or more of the sidewalls has an outer surface and defines a pocket along the outer surface at the taper. The taper may protrude toward a center point of the unit cell. Optionally, the core is a single monolithic body, the plurality of unit cells being joined together at a seamless interface. Optionally, the unit cells are arranged in rows at least partially stacked on top of each other. A line extending from a center point of one unit cell in the first row to a center point of another unit cell in the second row may define an angle of not less than 30 degrees and not more than 60 degrees with respect to a plane of the first row. Optionally, the unit cell defines no more or less than six apertures.

In one or more embodiments, a method for forming a core of a delivery device includes additively manufacturing the core by sequentially depositing layers of material at least partially over each other along a build direction to form a structure comprised of a plurality of connected unit cells. At least one of the plurality of connected unit cells has one or more sidewalls that are curved and have an inner surface that defines at least a portion of an internal passageway within and through the unit cell. One or more sidewalls of the cell lattice define a plurality of apertures such that the first fluid may enter the cell lattice through one of the apertures and may exit the cell lattice through another of the apertures. The one or more sidewalls include a taper disposed between at least some of the apertures of the unit cell. One or more of the sidewalls has an outer surface and a pocket is defined along the outer surface at the taper. The one or more sidewalls have edges that extend around the apertures of the unit cells, and the edges of different unit cells are connected to each other. The outer surface at least partially defines an external passage sealed from the internal passage by one or more sidewalls of the unit cell. The external passageway is configured to enable a second fluid to flow therethrough. One or more sidewalls of the unit cell can transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the internal passage to the second fluid flowing in the external passage without mixing the first fluid with the second fluid.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description may include instances where the event occurs and instances where it does not. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about", "substantially" and "approximately", may not be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, and such ranges may be identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The claims define the patentable scope of the disclosure, and include other examples that occur to those of ordinary skill in the art. Other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A core, comprising:

a structure having a plurality of connected unit cells, at least one of the plurality of connected unit cells having one or more sidewalls that are curved and have an inner surface that defines at least a portion of an internal passage within and through the unit cell, the one or more sidewalls of the unit cell defining a plurality of apertures such that a first fluid can enter the unit cell through one of the apertures and can exit the unit cell through another of the apertures, the one or more sidewalls including a taper disposed between at least some of the apertures of the unit cell, the one or more sidewalls having an outer surface and defining a pit along the outer surface on the taper, and

the one or more sidewalls have edges extending around apertures of the unit cells, wherein edges of different unit cells are interconnected and the outer surface at least partially defines an outer passage sealed to the inner passage by the one or more sidewalls of the unit cells, the outer passage configured to enable a second fluid to flow therethrough, the one or more sidewalls of the unit cells configured to transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the inner passage to the second fluid flowing in the outer passage without mixing the first fluid with the second fluid.

2. The core of claim 1 wherein the taper protrudes toward a center point of the unit cell.

3. The core of claim 1 wherein the unit cell defines at least three apertures and the taper is located equidistant from the at least three apertures.

4. A core as claimed in claim 3 wherein the taper is located equidistant from three of the orifices spaced 120 degrees from each other along the circumference of the unit cell.

5. The core of claim 1 wherein the unit cell has a spherical shape defined between the apertures by portions of one or more sidewalls of the unit cell and spaced apart from the taper.

6. The core of claim 1 wherein the wall thickness of the sidewalls of the unit cell is not less than 0.3mm and not greater than 1.5mm.

7. The core of claim 1 wherein the orifice diameter of the unit cell is at least ten times the wall thickness of one or more sidewalls of the unit cell.

8. The core of claim 1 wherein the core is a single monolithic body, the plurality of unit cells being joined together at a seamless interface.

9. The core of claim 1 wherein the structure is comprised of one or more of a metallic material or a polymeric material.

10. The core according to claim 1, wherein the unit cells are arranged in rows at least partially stacked above each other, and a line extending from a center point of one unit cell in a first row to a center point of another unit cell in a second row defines an angle of not less than 30 degrees and not more than 60 degrees with respect to a plane of the first row.

11. The core of claim 1 wherein the apertures of the unit cell have a diameter greater than a diameter of the external passage.

12. The core of claim 1 wherein the taper is a first taper, the one or more sidewalls of the unit cell comprise a second taper, the second taper disposed between a set of apertures of the unit cell different from the apertures between which the first taper is disposed; the first cone and the second cone protrude in a common direction.

13. The core of claim 12 wherein the structure has a height extending from a bottom end of the structure to a top end of the structure, the first taper of the unit cell being disposed below the second taper of the unit cell along the height, the first taper having a dimension greater than a dimension of the second taper.

14. A core, comprising:

a structure having a plurality of connected unit cells, at least one of the plurality of connected unit cells having one or more sidewalls that are curved and have an inner surface that defines at least a portion of an internal passage within and through the unit cell, the one or more sidewalls of the unit cell defining at least four apertures such that a first fluid can enter the unit cell through one of the apertures and can exit the unit cell through another of the apertures, a portion of the one or more sidewalls disposed between three of the apertures having a triangular shape and the three apertures being spaced 120 degrees from one another along a circumference of the unit cell, and

the one or more sidewalls have edges extending around apertures of the unit cells, wherein edges of different unit cells are connected to one another to at least partially define an external passage sealed to internal passages of the unit cells and internal passages of other unit cells by the one or more sidewalls of the unit cells, the external passage configured to enable a second fluid to flow therethrough, the one or more sidewalls of the unit cells configured to transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the internal passage to the second fluid flowing in the external passage without mixing the first fluid with the second fluid.

15. The core of claim 14 wherein the portion of the one or more sidewalls having the triangular shape comprises a cone, the one or more sidewalls having an outer surface and defining a dimple on the cone along the outer surface.

16. The core of claim 15 wherein the taper protrudes toward a center point of the unit cell.

17. The core of claim 14 wherein the core is a single monolithic body, the plurality of unit cells being joined together at a seamless interface.

18. The core according to claim 14, wherein the unit cells are arranged in rows at least partially stacked above each other, and a line extending from a center point of one unit cell in a first row to a center point of another unit cell in a second row defines an angle of not less than 30 degrees and not more than 60 degrees with respect to a plane of the first row.

19. The core of claim 14 wherein the unit cell defines no more or less than six apertures.

20. A method for forming a core, comprising:

additively manufacturing a core by depositing layers of material at least partially over one another in sequence along a build direction to form a structure comprised of a plurality of connected unit cells, wherein at least one of the plurality of connected unit cells has one or more sidewalls that are curved and have an inner surface that defines at least a portion of an internal passage within and through the unit cell, the one or more sidewalls of the unit cell defining a plurality of apertures such that a first fluid can enter the unit cell through one of the apertures and can exit the unit cell through another of the apertures, the one or more sidewalls including a taper disposed between at least some of the apertures of the unit cell, the one or more sidewalls having an outer surface along which a pocket is defined on the taper, and

the one or more sidewalls have edges extending around apertures of the unit cells, wherein edges of different unit cells are connected to one another, the outer surface at least partially defines an external passage sealed to the internal passage by the one or more sidewalls of the unit cells, the external passage configured to enable a second fluid to flow therethrough, the one or more sidewalls of the unit cells configured to transfer one or more portions of thermal energy from the first fluid or a component of the first fluid flowing in the internal passage to the second fluid flowing in the external passage without mixing the first fluid with the second fluid.